mybatis注解映射SQL

注解@Insert @Update @Select @ Delete

举例说明注解的用法：
public interface StudentMapper
{
    @Insert("insert into student (stud_id, name, email, addr_id, phone)values(#{studId},#{name},#{email},#{address.addrId},#{phone})")
    int insertStudent(Student student);
}
public interface StudentMapper
{
    @Insert("insert into student (name,email,addr_id,phone)values(#{name},#{email},#{address.addrId},#{phone})")
    @Options(useGeneratedKeys=true,keyProperty="studId")
    int insertStudent(Student student);
}
public interface StudentMapper
{
    @Insert("insert into student (name,email,addr_id,phone)values(#{name},#{email},#{address.addrId},#{phone})")
    @SelectKey(statement="select stud_id_seq.nextval from dual",keyProperty="studId",resultType=int.calss,before=true)
    int insertStudent(Student student);
}

@Update("update students set name=#{name},email=#{email}")
int updateStudent(Student student);

@Delete("delete form students where stud_id=#{studId}")
 int deleteStudent(int studId)

@Select("select name,email,phone from students where stud_id=#{studId}")
Student findStudentById(Integer studId);

结果注解

@Select("select name,email,phone from students where stud_id=#{studId}")
@Results({
    @Result(id=true,column="stud_id",property="studId"),
    @Result(column="name",property="name"),
    @Result(column="email",property="email"),
    @Result(column="phone",property="phone")
})
Student findStudentById(Integer studId);

结果注解有一个缺点，就是在一个查询方法前面都要写一遍，不能重用。解决这个问题方案是：
定义一份结果映射文件如下所示：



.......


@Select("select name,email,phone from students where stud_id=#{studId}")
@ResultMap("com.mybatis3.mappers.StudentMapper.StudentResult")
Student findStudentById(Integer studId);

动态Sql的注解

对于动态sql，mybatis提供了不同的注解，@InsertProvider @UpdateProvider @DeleteProvider @SelectProvider
用法如下所示：
首先创建一个provider类：
    
    public class SqlProvider
    {
        public String findTutorById(int tutorId)
        {
            return "select tutorId,name,email from tutors where tutorId="+tutorId;
        }
    }
 使用provider类：
     @SelectProvider(type=SqlProvider.class,method="findTutorById")
     Tutor findTutorById(int tutorId);   
  但是使用字符串连接创建sql语句容易出现问题，所以mybatis提供了一个SQL工具，简化了构建动态Sql的方式；
  如下所示：
    public class SqlProvider
    {
        public String findTutorById(int tutorId)
        {
            return new SQL(){{
              SELECT("tutorid,name,email")
              FROM("tutors")
              WHERE("tutorid="+tutorId)
            }}.toString();
        }
    } 
    或者 
    public class SqlProvider
    {
        public String findTutorById()
        {
            return new SQL(){{
              SELECT("tutorid,name,email")
              FROM("tutors")
              WHERE("tutorid=#{tutorId}")
            }}.toString();
        }
    }    

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